Brake lining for partial-lining disc brakes

ABSTRACT

A brake lining for partial-lining disk brakes, particularly of rail vehicles, wherein several friction or lining elements are provided which can be fastened to a support plate individually or in groups, in which case several support plates are arranged either directly on the lining holder of the disk brake arrangement or on a lining support which can be fastened to the lining holder. For rendering the surface pressure generated during the braking uniform, the support plates are swivellably linked to the lining support or lining holder, in the case of a group-like assignment, several (at least two) lining elements being swivellably arranged on the support plate. In the center of gravity of lining elements which are assigned to one another in groups, the respective direct introduction point of the lining contact pressure forces is situated, in which case centers of gravity of the surfaces of lining element groups assigned to one another in the triangle each have the higher-ranking position of the introduction of force of the brake operating elements.

This application is the U.S. national phase application of PCTInternational Application PCT/DE95/01139 filed Aug. 25, 1995.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a brake lining and more specifically to brakelining for partial lining disc brakes.

Large-surface brake linings, for example, rail vehicle disc brakes, haveno even approximately constant surface pressure on their frictionsurface during high-energy braking operations. This is, among others,the result of a non-uniform introduction of force from the brakeapplication device, for example, when dovetail guides are used. It alsoresults from accidentally warmer areas of the surfaces of the lining andthe brake disc, because of the thermal expansion of the frictionmaterials, bulge out of their surfaces, in which case these areas aremore stressed and, as the braking progresses, therefore become hotterthan the adjacent zones. The result of such "hot spots" on the disc andthe lining are premature hot cracks on the disc and lining damagebecause of thermal overloading. Particularly, with respect to hardlining materials (resin-bound materials, metallic sintered materials),the above-mentioned occurrence is extremely pronounced.

For avoiding the above-mentioning disadvantages--mainly when sinteredmaterials are used--brake linings were used which have elasticallydisposed individual elements (German Patent Document DE-OS 43 01 006).However, in the case of such arrangements, essentially two disadvantagesare found: The surface pressures on the individual elements are stillnot constant; they are a function of the compression corresponding tothe respective surface constant of the elastic bedding of the individualelements. In addition, the lining expenses on the whole are very highand therefore result in high costs. The price is four to six timeshigher than organically bound, one-piece linings.

In the case of a known brake lining of this type (CA-2120392), supportplates supporting lining elements are swivellably arranged on a supportbody in the form of a support plate. The lining elements are in eachcase rigidly connected with the support plate which, in turn, is rivetedto the support plate. Three lining elements respectively are situated inthe three corners of such a support plate which has the shape of atriangle. The rivets, which are used for connecting the support platewith the carrying plate, are in each case placed in the center area ofthe three legs of the triangular support plate so that the free cornersof the support plate can carry out pitching movements with respect tothe carrying plate to a limited extent. For this purpose, the supportplates are provided with weakenings in their center. Because of such ageometry of the positioning of the lining elements and of the fasteningof the support plate on the actual carrying plate, the swivel angle aswell as the swivel direction of the lining elements is given within anarrow scope; that is, the swivel axis of each lining element remainsgenerally constant. Despite the weakenings situated in the center of thesupport plates, a certain interdependence of the movements of one liningelement with respect to the next one is to be accepted because swivelmovements in one corner can be transferred beyond the center of thesupport plate to the area of the respective adjoining two liningelements. The result are undesirable oblique positions of the liningelements, that is, reactions of a lining element with respect to a trackon the brake disc are partially also transmitted to the closest liningelements. In addition, by means of the lining elements, no equal-surfacegrinding pattern can be achieved because the swivel angles or rotatingangles are fixed. The result are "hot spots" on the brake disc becauseresilient restoring forces, as increased reaction forces, can lead totemperature increases on the disc.

Based on the above, it is an object of the invention to develop a brakelining of the above-mentioned type by constructionally simple devicessuch that the surface pressure on the friction surface of the brake disccan be rendered more uniform. A clearly defined distribution of theoverall brake application force to the individual lining elements is tobe permitted. For saving expenses, it must also be possible to exchangethe brake linings or parts thereof at reasonable cost.

The objects are achieved by dividing the whole lining into severallining elements or group elements and as the result of the bearing ofthe lining elements or group elements on a bearing body, including thefixing of the introduction of the brake application force, a uniformdistribution of this brake application force to a plurality ofindividual lining elements or lining blocks is made possible. Inaddition, the lining elements or group elements form small exchangeableunits, which constitutes a significant reduction of price in contrast toconventional brake linings with a dovetail guide. In the case of liningelements arranged symmetrically with respect to the center line of thebearing body (lining support or lining holder) or lining groups formedof lining elements, the division of the overall lining into two halflinings is possible, in which case one lining element per support platecan be provided as the smallest lining unit. The lining elements or thegroups formed by them (group elements) with the support plate carryingthem can be arranged either on a common lining support or directly onthe lining holder. The type of the bearing of the lining elements on thesupport plates, the type of the bearing of the support plates on theirsupport, the lining support or the lining holder as well as the type ofthe introduction of the brake application forces with respect to theformed centers of gravity are responsible for rendering the surfacepressure uniform. Preferably, the bearing of each individual element,thus of each lining block on the support plate, consists of the pairingof a ball socket with a universal ball joint which is constructed suchthat the resulting force consisting of the contact pressure force on thebrake lining and the friction force perpendicularly thereto is in eachcase perpendicular to the spherical surface existing on the ball socket.In this case, the resultant force extends through the center of gravityof the surface of the respective lining element in the area of thefriction on the brake disc. When the surface pressure on the overalllining is rendered uniform, thus the loading of the brake disc is moreuniform, a higher energy absorption of the disc is permitted when thetemperature limit is reached. The wear is also lower because the wearrises superproportionally with the temperature and, when the temperatureis rendered uniform or reduced, a reduction of the wear is achieved.Naturally, when the surface pressure is rendered uniform and the brakedisc loading is more uniform, the danger of the formation of hot cracksis also reduced.

Another important advantage of brake linings of the above-mentioned typeare the much more favorable operating costs since the individual liningelements or group elements formed of lining elements are considerablyless expensive than the previously used dovetail lining elements in theelement construction or overall construction. While, in the case ofone-piece brake linings of the known type but also in the case of newermulti-part brake linings, it is required to exchange during a liningexchange also the comparatively expensive lining support, because of thedivision into lining groups or individual elements, in each casesupported by a low-cost support plate, it is possible to reuse thelining support after another fitting with lining elements or liningelement groups. In their overall arrangement, the lining elementspreferably form a ring sector surface which is advantageous with respectto the braking geometry, whereby a lower concave running slope of thedisc must be accepted. The friction elements or lining elements may havea circular shape, but may also have a polygonal form. In addition, theymay have torsional resistances or may be shaped such that they mutuallysupport each other in a locking manner against torsion.

In an advantageous further development, three individual elementsrespectively can be combined to form a common lining element, which isuseful in the case of rubber-based organic lining materials. It ispossible to fasten the lining elements in a multiple and articulatedmanner on their direct support, that is, on the support plate; thus, bymeans of riveted joints, weld point connections, screwed connections,etc. The targeted introduction of the brake applications forces on abrake lining of the type to be used is of special significance. Thus,the introduction of loads from the brake application device can takeplace by a ball joint, specifically in each case in the center ofgravity of a half-lining. It is also possible to introduce the overallbrake application force by way of a balance arm which distributes thebrake application force from a common lever uniformly to bothhalf-linings.

In the case of one-piece support plates as lining supports for thelining elements or group elements, a certain swivellability is possiblein the area of the common center line of the support, for example, as aresult of a weakening of the material. This ensures that the leverforces pressing in the center of gravity of the two half-linings areuniformly distributed on the triangle points or centers of gravity ofthe individual or group elements (statically determined resolution offorces).

Advantageous developments and further developments are listed inadditional claims.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of theinvention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the brake lining consisting of severalgroup elements with respect to the friction surface of a schematicallyindicated brake disc, in which case, for showing the geometricassignment, the lining support and the lining holder are not shown;

FIG. 2 is an individual sectional view of Line II--II in FIG. 3 showingthe linking of two lining elements to a support plate and its assignedto the lining support;

FIG. 3 is a top view of the arrangement according to FIG. 2;

FIG. 4 is a diagrammatic individual sectional view which is enlargedwith respect to FIGS. 2 and 3 and which shows the force on an individuallining element in its assignment to the support plate;

FIG. 5 is a bottom view of a lining support with group elements linkedto it which each consist of a support plate with three lining elementsrespectively;

FIG. 6 is a longitudinal view of a lining holder used for holding thelining support according to FIG. 5;

FIG. 7 is a diagrammatic view with respect to FIGS. 5 and 6 of a liningholder showing the centers of gravity D1, D2 and D3 formed by directlylinked group elements and the joint centers of gravity formed of thecenters of gravity of the group elements for the introduction of halfthe brake application force per lining half;

FIG. 8 is a view of a lining holder which can be compared with FIG. 7and has lining elements which are arranged directly on it, in which casethree individual elements per support plate are in each case combined toform a common lining element;

FIG. 9 is a sectional view which can be compared to FIG. 2 and showing aquasi articulated arrangement of the lining elements on the supportplate; and

FIG. 10 is a view, which can be compared to FIGS. 2 and 9, of a flatlinking of the lining elements to the support plate and the liningsupport in its assignment to the lining holder.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 of the drawing shows a brake lining consisting of several groupelements 1 with lining elements 3 in its assignment to the frictionsurface 5 of a brake disc 6 indicated in its circumferential lines andconsisting, for example, of steel. The group elements 1 are in each caseformed of the lining elements 3 and a support plate 7 supporting them.In the illustrated embodiment, there a 6 group elements 1 of this typewith three lining elements 3 constructed as braking blocks; thus thereare a total of eighteen lining elements 3. The lining elements arepreferably arranged in their overall surface as a ring sector surface,as illustrated in FIG. 1 and may, for example, consist of a sinteredmetal.

In the embodiment according to FIG. 1, three friction or lining elementsrespectively are arranged on a support plate 7 in a manner explained inthe following. The shown support plates 7 have, for example, atriangular shape, in which case the lining elements 3 are linked with acertain degree of swivelling freedom to the side of the support plates 7facing the friction surface of the brake disc.

According to FIG. 2, which illustrates a cross-section line II--II inFIG. 3, each of the lining elements 3 is linked to the support plate 7by a countersunk screw 9, a spherical cap 11, a pressure spring 13 and anut 15. The countersunk screw 9 is situated in a center recess 17 of thelining element 3 and extends in the shown manner through bores of thespherical cap 11 and of the support plate 7. With the interposition ofthe pressure spring 13, a counterscrewing by the nut 15 is provided. Thespherical cap 11 is inserted into a shell-shaped recess of the supportplate 7; the bearing of each lining element is therefore formed by aball socket and a universal ball joint. According to FIG. 4, whichschematically shows the guiding of one of the lining elements on thesupport plate 7, the forces F_(R) as the friction force and the contactforce F_(A) act upon the lining element 3, by means of which theresulting force F is formed. This force F extends in each caseperpendicularly to the spherical surface of the ball socket. The centerpoint of the radius r is placed in the center of gravity of the frictionsurface of the lining element 3. The resulting force F therefore extendsnecessarily through the center of gravity of the surface of the liningelement. Only in this manner can an approximately constant surfacepressure P of the lining element 3 be achieved with respect to thefriction surface 5 of the brake disc.

The arrangement of the lining blocks or lining elements on the supportplate 7 discussed with reference to rendering the contact pressure forceuniform also applied in the same manner to the arrangement of theindividual support plates 7 on a lining support 19 in the formillustrated, for example, in FIG. 5. The lining support 19 is providedas a support plate in order to hold the support plates 7 schematicallyillustrated in FIG. 1. In this case (FIG. 2), a screw 21, a sphericalcap 23, a pressure spring 25 and a nut 27 are again assigned to each ofthe support plates. The individual support plates 7 are thereforemounted in the same manner as the lining elements with a certain degreeof swivelling freedom on the lining support 19. As a bottom view, FIG. 5shows three of the support plates 7 on a lining support 19, whichsupport plates 7 each have three lining elements 3 arranged on them.

The lining support 19 with the eighteen lining elements arranged on itcan, in turn, be mounted on the lining holder 29 illustrated in a rearview in FIG. 6. The lining holder 29 has eyes 31 which are used for thesuspension on a hanging lug and carries the lining support 19 of anessentially comparable configuration on its side facing the brake disc.For this purpose, the lining holder 29 is provided, for example, on itsend, which is on the bottom in FIG. 6, with a bolt which can be bracedby a spring clip 33 and which, on the side facing away with respect tothe representation according to FIG. 6, reaches through one of the eyes35 of the lining support. Additional fastening elements (not shown)extending from the lining support 19 can be guided through openings ofthe lining holder 29 and can be screwed together with respect to thelining holder 29. The lining support 19, together with the liningelements 3 arranged on it, can thereby be demounted rapidly from thelining holder 29 since, after the detaching of the above-mentionedfastening elements or the pulling-out of the holding bolt which can bebraced by the spring clip 33, a pulling-off of the lining support 19transversely to the lining holder 29 is made possible.

The support plates 7 with the lining elements 3 were explained as beingheld on a lining support 19 with reference to FIGS. 2 and 5, in whichcase the lining support 19 itself can be fastened on a lining holder 29(FIG. 6). For certain applications, a direct fastening of the supportplates 7 on the lining holder 29 (FIG. 7) is also provided.

An important characteristic of the holding of the lining for the purposeof rendering the surface pressure uniform is the geometric arrangementof the individual lining elements 3, of the support plates, carryingthem and their arrangement on a support body (lining support 19 orlining holder 29). The direct holding of the support plates 7 on alining holder 29 illustrated schematically in FIG. 7 shows that theindividual group elements 1, which consist of three lining elements 3each carried by a support plate 7, have a common center of gravity D1,D2 and D3 as the introduction point of the lining contact pressureforces. The centers of gravity D1, D2 and D3 of the three group elements1, in turn, form a triangle whose center of gravity S forms the forceintroduction point of half the overall brake application force perlining for each disc side. In this case, it should be assumed that twohalf linings with nine lining elements respectively on three supportplates respectively are conceivable on both sides of the center axisA--A. Therefore, two centers of gravity S exist for each overall lining.The load introduction points of the brake levers 37 shown schematicallyin FIG. 7 or corresponding pressure points of hydraulic or pneumaticbrake pistons (not shown) are situated at both centers of gravity S.Preferably, one spacer respectively is provided in the area of theintroduction of force, that is, in the area of the center of gravity S,such that an almost punctiform transmission of forces is permitted fromthe lining holder 29 to the lining support 19. The spacers can be formedon one of the mutually facing surfaces of the lining support 19 or thelining holder 29. The contract pressure forces, which are introduced bythe brake levers 37 to the halves of the overall lining which are on thetop and on the bottom in FIG. 7 and which in each case correspond tohalf the overall brake application force per lining, are introducedtherefore by way of the centers of gravity S or D1, D2 and D3 uniformlyinto the support plates 7. The support plates 7 and the lining elements3 arranged on them have the above-explained bearing so that, on thewhole, the surface pressure of the overall lining becomes uniform. Onthe whole, a more uniform brake disc loading is achieved (constantenergy supply by way of the friction surface) and the danger of a hotcrack formation is therefore reduced. An additional important advantageis the no-squeal braking performance of the lining elements because theywill not "rise" because of their bearing according to the invention.

As far as the introduction of loads to the lining holder is concerned,it can be provided from both sides of the brake application device byway of a ball-and-socket joint, specifically in each case in the centerof gravity of a half lining, as explained above with reference to FIG.7. The division of the lining into two half linings, when in each casehalf the brake application forces are introduced, requires that acertain inherent mobility is possible between the two halves of thelining support (FIG. 7). FIGS. 5 and 7 show that, in the area of thecenter line A--A of the lining support 19 or lining holder 29, aweakening of the material formed by a window or a recess 47, 49 isprovided such that the halves of the lining support or holder can beswivelled to a limited extent with respect to the center line A--A,which, in conjunction with the center-of-gravity-related introduction offorces, contributes to the fact that the contact pressure forces becomemore uniform. For the purpose of the introduction of the brakeapplication forces, it is particularly important to operate by means ofa balance arm which can uniformly distribute the brake application forcefrom a common lever to both half linings. In this case, the common leverextends in the center to the lining support 19 or lining holder 29.

The lining elements 3, which are shown to be hexagonal in FIGS. 2, 3 and5, may have any other configuration. They may, for example, be round,which is shown schematically by FIGS. 1 and 7. Although preferably threelining elements 3 are provided per support plate 7, their number canalso vary, assuming in each case that the introduction of the contactpressure forces as the result of the geometric assignment of the centersof gravity results in uniformity. It is also possible to combine threelining elements respectively to form a single element. This is useful,for example, in the case of a rubber-bound, organic lining material.FIG. 8 shows such an arrangement. Three heart-shaped lining elements areprovided per lining half; therefore, a total of six lining elementswhich are held by support plates 7. As in the case of the embodimentaccording to FIG. 7, the support plates 7 are swivellably arrangeddirectly on the lining holder 29, in which case the introduction offorce again takes place per lining half in the central center of gravityformed by the individual centers of gravity of the three liningelements.

According to FIG. 9, the individual elements or lining elements can alsobe arranged in a "quasi articulated" manner on the support plate 7;thus, for example, by riveting, weld point connection, by a screwedconnection, etc. The spacer 39 provided in the embodiment according toFIG. 9, which are each inserted between the lining elements 1 and thesupport plate 7, permit the required limited swivellability for thepurpose of rendering the contact pressure forces uniform. Naturally, itis also possible to construct the individual elements or a portionthereof to be resistant to torsion (for example, by means of a pin andbore).

FIG. 10 of the drawing shows a holding of the lining elements 1 on thesupport plate 7 and a holding of the support plate 7 on the liningsupport 19 which are of a much lower depth than in the comparable viewaccording to FIG. 3. Holding pins 41 are provided which are comparableto the countersunk screws 9 and which each reach through bores in thelining element 3, in a spherical cap 43 and in the support plate 7. Thecup springs 45 reach behind the holding pins 41 such that the liningelements are pulled to the support plate 7 by spring force. The holdingand bracing of the support plate 7 with respect to the lining support 19is constructed in the same manner. The advantage of the arrangementaccording to FIG. 10 is that, for demounting the lining support 19 fromthe lining holder 29, no vertical movements are required relative to it.After the detaching of the pin holding arrangement indicated withreference to FIG. 6, the lining support 19 can be pulled off laterallyor on the front side. As a result, it is very simple to detach thelining support 19 without demounting the lining holder 29 so that acomplete exchange of the lining support 19 can be carried out within avery short time. As required, it is also possible to exchange individuallining elements 3 and/or individual support plates 7 with liningelements 3 held on it. This represents an important advantage withrespect to known constructions with a so-called dovetail guide, whereinone-piece brake linings, after they are worn out, must be exchangedtogether with their lining support, while the construction of the brakelining according to the invention provides another use of the liningsupport and possibly also of the support plates.

I claim:
 1. A brake lining for partial-lining disc brakes comprising:asupport body; a plurality of support plates being swivellably held onthe support body; a plurality of lining elements mating with saidsupport plates at a ball-and-socket joint; a plurality of holdingelements mounting the lining elements to the support plates; and aspring on each holding element biasing the lining elements and supportplates towards each other.
 2. A brake lining according to claim 1,wherein the lining elements include a universal ball joint in a ballsocket of the support plates.
 3. A brake lining according to claim 1,whereinseveral group elements are provided per lining half which areeach formed of plural lining elements and a support plate, the groupelements have an introduction point of the lining contact pressureforces on their center of gravity, and the centers of gravity of atleast three group elements of each lining half form a triangle whosecenter of gravity forms the force introduction point of half the overallbrake application force per brake lining for each disc side.
 4. A brakelining according to claim 3, wherein the support body includes aplate-shaped lining support and a lining holder of the disc brake, thegroup elements are swivellably linked to the lining support, and thelining support is fastened to the lining holder in a quickly detachablemanner.
 5. A brake lining according to claim 3, wherein the support bodyincludes a lining holder of the disc brake, and the group elements areswivellably arranged directly on the lining holder.
 6. A brake liningaccording to claim 3, wherein the support body includes a lining holderof the disc brake, and the support plates are swivellably arrangeddirectly on the lining holder.
 7. A brake lining according to claim 1,wherein the support body includes a plate shaped lining support and alining holder of the disc brake, the support plates each carry a singlelining element and are swivellably linked to the plate-shaped liningsupport, and the lining support is fastened on the lining holder.
 8. Abrake lining according to claim 1, wherein the support body includes alining holder of the disc brake, and the support plates each support asingle lining element and are swivellably arranged directly on thelining holder.
 9. A brake lining according to claim 1, wherein saidsupport body includes a lining support, a lining holder of the discbrake and, in the area of the introduction of force of the two lininghalves, one spacer plate respectively between the lining support and thelining holder such that the force transmission takes place from thelining holder to the lining support in the area of the spacer plate. 10.A brake lining according to claim 1, wherein said support body includesa lining support, the support plates are linked to the lining support,and the lining support can be swivelled in the area of its center lineto a limited extent about this center line.
 11. A brake lining accordingto claim 10, wherein the lining support includes a weakening of thematerial in the area of its center line.
 12. A brake lining according toclaim 1, wherein said support body includes a lining holder of the discbrake, said support plates are linked directly to the lining holder, andthe lining holder can be swivelled in the area of its center line to alimited extent about this center line.
 13. A brake lining according toclaim 12, wherein the lining holder includes a weakening of the materialsituated in the area of the center line of the lining holder.
 14. Abrake lining according to claim 1, wherein the support body includes aplate-shaped lining support and a lining holder of the disc brake, thesupport plates are swivellably linked to the lining support, and thelining support is fastened to the lining holder in a quickly detachablemanner.